This application claims the priority of Germany priority document 100 12 411.9, filed Mar. 13 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a process for computing the coefficients of a space-time adaptive processing (STAP) filter, and for filtering radar source data of the distance Doppler matrices of two adjacent reception channels by means of space-time adaptive processing.
Radar source data consist of a mixture of signals (such as echoes from moving and stationary targets) and interferences (such as noise). As a rule, when analyzing these radar source data, interferences are to be suppressed so that the signals can be easily detected.
To improve the detection of moving targets (or example, in SAR images), it is necessary to suppress interference signals as well as signals which originate from stationary targets. A suitable process for this purpose is space-time adaptive processing (STAP). In known processes for this purpose, the radar source data are as a rule filtered in the time domain.
It is an object of the invention to compute and implement in a simple manner, within the scope of the STAP processing, the filter coefficients and the filtering of the radar source data of the distance Doppler matrices {right arrow over (X)}left and {right arrow over (X)}right of two reception channels, so that use of this STAP filter is permitted in real-time systems.
This and other objects and advantages are achieved by the process according to the invention, in which in contrast to conventional STAP filters, computation of the coefficients and the filtering is performed exclusively in the frequency domain. Similar to the xe2x80x98fast foldingxe2x80x99, a considerable advantage is therefore obtained with respect to the necessary processor performance.
The theoretical basis of the process according to the invention resides in the proposition that the Doppler frequency and the phase difference are correlated in the case of typical SAR source data, in the signal spectrum of two adjacent channels.